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(No Model.)

Patented Aug. 28, 1883.

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UNITED Srarns PATENT Crricn.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGN-MENTS, TO THE WESTERN ELECTRIC COMPANY, OF SAME PLACE.

CIRCUIT FOR TELEPHONE CALL-BOXES.

SPECIFICATION formingpart of Letters Patent No. 283,927, dated August28, 1883. Application filed February 24, 1881. (No model.)

To aZZ whom it may concern:

Be it known that I, CHARLES'E. Scnrnnnn, of Chicago, Cook county,Illinois, have discovered certain new and useful Improvements 5 inCircuits for Telephone CalLBOXes, of which the following is a full,clear, concise, and exact description, reference being had to theaccompanying drawing, forming a part of this specification.

1 The object of my invention is to provide,

for the telephone outfit furnished to subscribers, a circuit so arrangedin connection with a switch on the box that when the switch is in oneposition the telephone-line is connected V I to the call-bell of thesubscriber, while at.

the same time the local battery of the transmitter is left open, and thereceiver, telephone, and secondary wire of the inductioncoil are shuntedout of the circuit. On chang- 2o ing the position of the switch thelocal battery of the transmitter is closed and the call-bell is shuntedout of the circuit, while the re ceiving-telephone and secondary wire ofthe induction-coil are brought into the circuit.

2 5 Herctofore this has been done by branching the line-wire through thebellin one direction and through the receiver and secondary of theinduction-coil in the other, and arranging the switch to vibrate betweenthe two points to which these two branch wires are respectivelyconnected, an additional point being pro vided 011 the switch forclosing the local circuit of the transmitter-battery. The lever of theswitch was connected through the mag neto-generator and thence to groundor the continuation of the line, as the case might be. The objection tothis arrangement is that the switch frequently fails to make connectionon the one point or the other, and the result is 40 that the circuit ofthe line is thereby left open.

In one case the system will be rendered inoperative for talking; in theother it will be impossible to ring the subscribers bell. This troubleis met with most frequently in boxes 5 having automatic switchesthat isto say, switches operated by hanging up and taking down thereceiving-telephone. By arranging the circuits as hereinafter described,a circuit is always maintained through the subscribers 5o outfit, thoughthe switch, whether automatic or otherwise, should make an imperfectcon,-

nect-ion or fail entirely to make connection at, either of the points.

In the drawing I have shown a diagram of the circuits which constitutemy invention.

A is the magneto-generator, B the receivingtelephone, C-the transmitter,and Dthe induction-coil.

The telephone-line coming from the central office passes in the usualmannerto a plate of the lightning-arrester, and thence, as indicated 1)lines aaa throu h the 1'eceivin -tele )hone and secondary of theinduction-coil and to the oth er plate'of the li ghtning-arrester, andthence to the ground, when the switch is in the position shown by thefull lines. The local eir cuit is indicated by dotted lines. When themetallic ring of the receiver is thrust upon the hook of the switch, asindicated by the dotted lines, the switch-lever is moved and contact 0at point d is broken, while thelines b and c are connected through themedium of the ring of the telephone, and the circuit of the telephoneline may be traced as follows: from the right plate of thelightning-arrester, by line (ta. to line b, and thence by line 0 throughthe callbell, which connects with line a near the left plate of thelightning-arrester, and to ground.

It will be seen that in one position of the switch the shunt-wire b ofthe telephone and secondary of the induction coil is broken, while theshunt of the call-bell will be broken at d, and the circuit of thetelephone-line will be directed, as indicated by line 0, through thecall-bell. Suppose, now, both shunt-lines 8 5- should be open. Thecircuit of the telephoneline would be through the receiver, thesecondary of the induction-coil, and, by line a, through the call-bell,and thence to ground; and the only difference would be the additionalre- 0 sistance of the magnets of the call-bell or that of thereceiving-telephone and secondary of the induction-coil, as the casemight be, left in circuit.

I disclaim the combination of the ring of 5 the telephone with. theswitch, this being the subj cot-matter of a prior application.

Under ordinary conditions, when shunt b is broken'shunt a is closed, andvice versa. If, however, through accident or mistake, both shunts shouldbe broken at the same time, the box will be operative, as beforedescribed.

I claimline a, and the switch, whereby the call-bell is 1. Thecombination of a teleph'oneswitch shunted. from the circuit; as and forthe pur- 10 with the shulgt-fillf a of the cilll-bellll and tllge poseset forth. 7

shunt-wire b 0 ereceivinge ep one su 5 stantially as and for the purposespecified. CHARLES SCBIBNER' r 2. The circuit of line a, passing throughthe XVitnesses:

telephone-receiver to the switch-lever, in com- GEORGE P. BARTON,

bination with line 0 through the call-bell, and JAMES L. BAIRD.

